The present invention relates to processing of semiconductor wafers and, more particularly, to a boat assembly used to hold semiconductor wafers or the like within externally excited, chemical reaction systems wherein the reactant flows over the wafers or workpieces that are held with their broad surfaces in perpendicular to the flow of the reactant.
Plasma enhanced chemical vapor reactors are known in the art wherein the plasma reactant gas or gasses flow across serially arranged workpieces perpendicular to the broad surfaces of the workpieces. For instance, U.S. Pat. No. 4,401,507, which is incorporated herein by reference made thereto, is exemplary of the type of plasma chemical vapor reactor to which the present invention is applicable. The chemical reactor systems of the type disclosed in the U.S. Pat. No. 4,401,507, utilize an evacuable tabular envelope retained in a furnace. A boat assembly that is removably inserted into the tabular envelope is used to hold workpieces perpendicular to the flow of the gas reactants that are passed through the tabular envelope during the depositing process of the workpieces. Of great concern in these chemical vapor reactor systems is the degree of process uniformities achievable. It is desirable to maintain the deposit thickness of film properties of the workpieces processed in the chemical reactors to maximum of .+-.5% from one end of the loaded boat assembly to the other. In addition, it is desirable to be able to process as many workpieces as possible during each chemical vapor deposition process.
Thus a need exists for an improved apparatus which can be utilized in contemporary plasma enhanced chemical vapor deposition reactors that can maintain the process uniformities below .+-.5% while allowing a larger number of workpieces to be processed at one time than is presently possible with conventional boat assemblies presently available.